Cutting machines for fibrous materials



July 17, 1962 A. RITSCHER ETAL 3,044,225

CUTTING MACHINES FOR FIBROUS MATERIALS Filed Dec. 12, 1958. 2 Sheets-Sheet 1 g INVENTORS:

July 17, 1962 A. RITSCHER ETAL 3,

CUTTING MACHINES FOR FIBROUS MATERIALS Filed Dec. 12, 1958 2 Sheets-Sheet 2 11v ENTOILS" 6 BY- I I am,

United States Patent G Claims The present invention relates to improvements in cutting machines for fibrous materials, such as tobacco or the like, and it particularly relates to the provision of an automatic grinding device for maintaining sharpness of the cutter blades of such machines.

For grinding flat blade cutters secured to the periphery of a rotary cutter drum of a tobacco cutting machine, grinding devices have been proposed in which a grinding wheel is reciprocated in a linear path and thereby the cutters of the cutter drum, which rotates at a high peripheral speed, are maintained in a sharp and efiective cutting condition. One or more such grinding devices may be distributed over the length of the cutter drum. The rectilinear reciprocation requires the provision .of a relatively complicated mechanism and a series of guides must be provided for the linearly movable parts; one object of the present invention is to provide a comparatively simple construction which avoids the necessity for incorporating the relatively complicated and expensive support and guide means which have heretofore been necessary.

The present invention is based on the provision of a pivotal or rotatable holder carrying a rotating grinding wheel at an eccentric point and moving in a plane tangential to the pitch circle of the cutter blades, i.e., to the surface swept by the edges of such blades, and wherein the diameter of the grinding wheel is at least equal to the chord height of the are described by the grinding wheel in the region of the tangent with the surface swept by the cutter blades.

For adjustment or setting of the grinding wheel the holder is displaceable relatively to the pivoted axis there of or is displaceable with it relatively to the machine frame and transversely to the cutter drum shaft. The drive for the holder is effected conveniently by means of a worm wheel secured to the holder and engaged by a Worm driven by a separate motor. A preferred form of the invention consists in the fact that the holder with the grinding wheel executes a pendular pivotal motion extending over the length of the cutter drum.

For controlling this pivotal motion electric contacts can be provided at the limits of movement of the path of the holder, and which reverse the driving motor for the holder at the end stroke points. The control of the pivotal motion can naturally also be effected mechanically or in any other way. By removal or shifting of one of the stops the grinding wheel holder can be readily moved out of the region of the cutter drum so that the grinding wheel is easily accessible for servicing or for replacement.

If some further complication may be accepted it is naturally also possible to utilise a grinding wheel holder rotating in a circular path which is provided with several arms arranged at an angle one to the other in the manner of a feed wheel, said angle corresponding to the angle executed by the backwards and forward swinging movement of a single-armed holder.

Also the grinding wheel holder can be rotatably mounted on the inner wall of a housing with the rotary axis of the holder arranged below that of the cutter drum shaft. Also in this case one or more grinding wheels can be provided.

The essential feature of the invention is the provision of a grinding wheel holder movable in a rotary path whereby a simple construction and an extremely smooth and accurate grinding of the cutters is made possible.

Two constructional examples of the invention are shown diagrammatically on the accompanying drawings wherein:

FIG. 1 is an elevation of one form of grinding device as seen in the direction of the arrow A in FIG. 2,

FIG. 2 is a view of this grinding device in the direction of the arrow B in FIG. 1,

FIG. 3 is a view of another form of grinding device in section on the line C--D in FIG. 4, and

FIG. 4 is a side view of this grinding device in section on the line A' of FIG. 3.

In FIGS. 1 and 2 a one-armed holdert7 is secured to a horizontal shaft 8 supported in a bearing 6 carried by the machine frame 1. The frame 1 has mounted therein a shaft 3 carrying a cutter drum 2. The other parts of 'the machine have not been shown as they are well known and do not form part of this invention. In FIG. 1 a single cutter blade 5 only of the drum 2 is shown and the cutting pitch circle 4 of the cutter is indicated in dotted lines. In this construction of the invention the shaft 8 carrying the holder 7 is rotatably and axially adjustab-ly mounted in the bearing 6. At the end of the holder 7 remote from the shaft 8 is mounted a cup-shaped grinding wheel 9 on a driven shaft 10. The holder 7 receives its rotary movement from a motor 11 (see FIG. 2) by means of a worm 12 secured to the motor shaft 11 and a worm wheel 13 secured to the holder 7. Another motor 14 mounted on the holder 7 drives the grinding wheel 9 by means of a V-belt drive 15.

The motor 11 is reversible and is reversed at the two desired end poistions 7' and 7" by any suitable electric switching devices not shown so that the holder 7 rocks backwards and forwards in pendular manner between the two end positions 7' and 7". The manner of mounting the cutter drum shaft 3 and this may be an automatic and gradually progressive movement to maintain a proper grinding action and the correct cutting conditions throughout.

The construction shown in FIGS. 3 and 4 embodies a rotary rather than a swinging motion; a cutter drum 21 rotates about a shaft'22 on which a skew gear 23 is fastened driving an intermediate shaft 24 by means of a further gear wheel. A spur wheel 25 fastened on the intermediate shaft 24 engages a toothed ring 26:: which forms part of a holder 26 for several grinding wheels 31 and spindles 30, one of which only is shown on the drawing, the holder 26 being in this case of disc form.

The holder 26 is rotatably supported in a housing 27 secured to the frame of the tobacco cutter. A motor 28 fastened to the housing 27 projects through the wall thereof and drives the grinding spindle 30 by means of a V-belt drive 29, the grinding wheel 31 being secured tothe spindle 3d at apoint facing the cutter drum 21.

The spindle 30 is displaceably mounted in the holder 26 and in a flange 32 secured to it, in order to permit adjustment of the grinding wheel 31. For this purpose a ring 33 provided with an external thread is slid on the grinding wheel spindle 3i} and is clamped between a ring 34 and a collar 35 on the grinding spindle. The ring 33 is prevented from rotation by a pin 36 and arranged within a worm Wheel 37 provided with a corresponding internal thread, the worm wheel being supported in the grinding wheel holder 26 and in the flange 32. The worm Wheel 37 is driven by means of a Worm 38 mounted one shaft 39 and rotatably supported in the holder 26. The worm 38 is rotated by a pivotal'lever 40 which includes a follower roller 41 co-operating with a cam 42, and the lever 40 is carried by means of a one-way drive device on the shaft 39 so that in one direction the lever 40 operates the worm 38 and on the return stroke, effected by the action of the spring 43, the shaft 39 is not rotated.

-By the resulting rotation of the worm wheel 37 the ring 33 is displaced towards the left and it moves the grinding wheel spindle 30 with the grinding wheel 31 towards the rotary cutter blades, 24 fastened to the cutter drum 21. Thereby the grinding wheel 31 is advanced a to a small extent towards the cutter blades 24 on each revolution of the grinding Wheel holder 26 thus main-. taining the optimum. cutting conditions.

In order that the pitch circle S shall be maintained constant an adjustably mounted diamond 4-5 is provided in a holder 44 and operates upon the grinding Wheels 31. Further the cutter blades are automatically fed forward inknown manner during the rotary movement thereof, the means for doing so being indicated in purely schematic form at 51, 52 in the form of driving worms and worm wheels respectively operatively coupled with the rotation of the cutter drum to impart a very gradual feed movement to the cutter blades. 2

What we claim is:

1. An automatically adjustable grinding device for the cutter blades of-a tobacco cutter drum rotatably mounted in a machine frame, comprising a pivot holder supported by said machine frame movable about a horizontal axis during the grinding operation, means including an electric motor mounted on said machine frame for moving said holder about said horizontal axis, a rotary shaft on said holder offset and parallel to the axis of said holder, a rotary grinding wheel secured to one end of said shaft at the free end of said holder having a radial grinding face and mounted on said shaft for movement with its radial grinding surface in a plane tangential to the rotary cutting surface of the cutter blades, the diameter of the grinding Wheel being at least equal to the chord height of'the are described by the grinding Wheel in the region of the tangent with the cutting surface, and automatic step by step means for intermittently and progressively advancing said grinding wheel toward said cutter blades during the grinding operation, the shaft and holder axis being arranged'to extend transversely of the cutter drum axis.

2. Grinding device according to claim 1, in which said electric motor is reversible so as to move said holder and the rotary grinding wheel thereon backwards and for,-

a pendular action.

3. Device according to claim 1, in which said holder consists of a rotary disc which has mounted thereon a plurality of grinding wheels in circumferentially spaced relation.

4. Device according to claim-1.3, in which said rotary disc is provided with external teeth engaged by :gear means driven by said cutter drum.

5. In a grinding device for sharpening the blades of a rotary tobacco cutter, a machine frame, a cutter drum rotatably mounted in said fname, cutter blades mounted on said drum extending the length thereof, a rotary grinding wheel having its radial face presented to the peripheral surface of said drum, a carrier for said grinding wheel movable about a horizontal axis offset from the axis of said grinding Wheel, means to support said carrier on said machine frame for motion in an arcuate path about said horizontal axis during the grinding operation so that the grinding wheel moves in a vertical plane tangential to the periphery of said 'drumin contact with said cutter blades throughout the entire length, means including an electric motor mounted on said machine frame for operatively moving said carrier and the grinding wheel thereon through a grinding cycle, said grinding wheel having a diameter chosen so that the surface area swept by the operative radial face thereof wholly embraces the line of Contact between the rotary path of the cutter blades and the plane tangential thereon in which the grinding Wheel is moved so as to grind. a true edge on said cutter blades along their entire cutting edge area.

6. A rotary tobacco cutter according to claim 5, in which said arcuate path is determined by a reciprocating motion imparted to the carrier by said electric motor.

7. A rotary tobacco cutter according to claim 6, including a reversible electric motor. for reciprocating the carrier, and contacts positioned at the end points of the reciprocatory movement of said carrier.

8. A rotary tobacco cutter according to claim 5, in which said arcuate path consists of a continuous rotary motion imparted to the carrier by said electric motor and wherein the carrier has mounted thereon a plurality of grinding-wheels moving in a common plane and presented successively'to the, grinding position.

9. In combination with a rotary tobacco cutter having a rotary drum arranged to rotate about a horizontalaxis and a plurality of circumferentially spaced cutter blades extending parallel to the axisof rotation of said drum, a grinding device comprising a rotary carrier to rotate about a horizontal axis normal to and offset from the axis of said drum, a shaft on said carrier offset from and parallel with the carrier axis, a grinding wheel rotatably mounted on said carrier having a radial grinding surface, motor means for rotating said shaft and grinding wheel and means for rotating said carrier, the radial face of said grinding-wheel being presented to the drum and movable in a plane tangent to the periphery of said drum to engage the cutter blades thereon during the grinding operation and rotational movement of said carrier, said grinding wheel being of a diameter such that the surface area over which said radial face moves will embrace the line of contact between the rotary path of the cutter blades as they move into and out ofsaid tangential plane, means for moving said grinding wheel intermittently in the direction of said cutter drum, a; grinding wheel truing device located in said tangential plane and remote from the line of contact of said plane with said drum and means for actuating said advancing means when the grinding wheel approaches said. truing device, the axis of said shaft and carrier being arranged to extend in a direction transversely of saiddrum axis.

10. A rotary cutting machine comprising ina machine frame a rotarycut-ter drum provided with cutter blades thereon, a carrier, means to support said carrier for pivotal motion about a horizontal axis during the grinding operation and in a plane tangential to said cutter drum, a shaft offset and parallel with said carrier axis, a grinding wheel on said shaft having a radial grinding surface mounted on said carrier to engage and grind said cutters, said grinding wheel having an effective diameter surpassing the chord height of the curved movement path of the grinding wheel in grinding contact with said cutter blades, a grinding wheel trueing means in said machine frame, and automatic means for intermittently and progressively feeding the grinding wheel gradually toward said cutter drum when said grinding wheel approaches said trueing means during pivotal movement of said carrier.

References Cited in the file of this patent UNITED STATES PATENTS Mason Dec. 20, Bolender July 1, Adamson June 20', Dearsley Dec. 26, Bowen July 15, Pollman May 20,

FOREIGN PATENTS Sweden May 2, France June 17, France July 22, Great Britain June 27, 

